Diffusion barriers have been used in thin film microelectronic structures where unwanted interaction between neighboring layers occurs. A notable case is the Al contact to Si. The interaction between Al and Si produces an Al penetration problem. To deal with the problem, a silicide layer is introduced between the Al the Si to serve as a diffusion barrier as well as a contact layer to Si. However, Al reacts quite easily with the silicide which still tends to defeat the purpose thereof. Hence, a second diffusion barrier, usually a refractory metal film such as Cr, has been added between the Al and the silicide. This remedy possesses the fundamental shortcoming that the multi-layered thin film structure is not at thermodynamic equilibrium. It depends on sluggish kinetics to achieve the effect of barrier. The interaction between Al and Si is slowed down, thereby buying more time before device impairment or failure. Therefore, there will be always a doubt about long term stability or reliability in the device. Structures of Al/Cr/PtSi/Si are known to fail.